While I do not know if any flags of the 8th USCT Regiment survive, I can speak to the flags they carried at the Battle of Olustee, Florida, on Feb. 20, 1864. Union infantry regiments, including the 8th USCT, usually were issued two flags. One was a national flag (an American flag) and the other was a regimental flag (typically blue and usually with a painted eagle). At the the Battle of Olustee, the 8th USCT, which had not had combat training, found itself under heavy fire and sustained heavy casualties. In the retreat they lost their national flag, which was left on the battlefield. The unit carried their regimental flag with them as they fell back.

A fanciful post-war illustration of the 8th USCT with their national flag at the Battle of Olustee can be found at:
http://www.flheritage.com/facts/reports/civilwar/olusteepic.cfm

A website with links to many historical resources regarding the 8th USCT:
http://princetonusct.blogspot.com/2007/05/8th-united-states-colored-infantry.html

I hope this information is helpful.

Sincerely,

Bruce G.